Notch signaling is required for proliferation but not for differentiation at a well-defined beta-selection checkpoint during human T-cell development.
Notch signaling is absolutely required for beta-selection during mouse T-cell development, both for differentiation and proliferation. In this report, we investigated whether Notch has an equally important role during human T-cell development. We show that human CD34(+) thymocytes can differentiate into CD4(+)CD8beta(+) double positive (DP) thymocytes in the absence of Notch signaling. While these DP cells phenotypically resemble human beta-selected cells, they lack a T-cell receptor (TCR)-beta chain. Therefore, we characterized the beta-selection checkpoint in human T-cell development, using CD28 as a differential marker at the immature single positive CD4(+)CD3(-)CD8alpha(-) stage. Through intracellular TCR-beta staining and gene expression analysis, we show that CD4(+)CD3(-)CD8alpha(-)CD28(+) thymocytes have passed the beta-selection checkpoint, in contrast to CD4(+)CD3(-)CD8alpha(-)CD28(-) cells. These CD4(+)CD3(-)CD8alpha(-)CD28(+) thymocytes can efficiently differentiate into CD3(+)TCRalphabeta(+) human T cells in the absence of Notch signaling. Importantly, preselection CD4(+)CD3(-)CD8alpha(-)CD28(-) thymocytes can also differentiate into CD3(+)TCRalphabeta(+) human T cells without Notch activation when provided with a rearranged TCR-beta chain. Proliferation of human thymocytes, however, is clearly Notch-dependent. Thus, we have characterized the beta-selection checkpoint during human T-cell development and show that human thymocytes require Notch signaling for proliferation but not for differentiation at this stage of development.
Taghon
Tom
T
Department of Clinical Chemistry, Microbiology, and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, Ghent, Belgium. Tom.Taghon@ugent.be
Van de Walle
Inge
I
De Smet
Greet
G
De Smedt
Magda
M
Leclercq
Georges
G
Vandekerckhove
Bart
B
Plum
Jean
J
D018952:Antigens, CD34 / Q000378:metabolism; D018106:CD28 Antigens / Q000378:metabolism; D015704:CD4 Antigens / Q000378:metabolism; D016827:CD8 Antigens / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D049109:Cell Proliferation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor / Q000502:physiology; D005799:Genes, Dominant / Q000502:physiology; D019674:Genes, T-Cell Receptor beta / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D051880:Receptors, Notch / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013601:T-Lymphocytes / Q000378:metabolism / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors
D018952:Antigens, CD34; D018106:CD28 Antigens; D015704:CD4 Antigens; D016827:CD8 Antigens; D004268:DNA-Binding Proteins; C430872:MAML1 protein, human; D051880:Receptors, Notch; D015534:Trans-Activators; D014157:Transcription Factors